GB2301790A

GB2301790A - Apparatus and method for pulp-moulding articles

Info

Publication number: GB2301790A
Application number: GB9611685A
Authority: GB
Inventors: David John Gillespie
Original assignee: David S Smith Packaging Ltd
Current assignee: David S Smith Packaging Ltd
Priority date: 1995-06-05
Filing date: 1996-06-05
Publication date: 1996-12-18
Also published as: GB9611685D0; GB9511282D0

Abstract

Apparatus 1 is shown and described for forming a moulded article from a settable pulp, comprising mould means 2 and setting means, the mould means 2 being adapted to contact the article over substantially its entire surface area, and to facilitate setting of the pulp via the setting means 10 whilst the article is in contact with the mould. Egg boxes may be made in this way, the major surfaces of the article, being smooth.

Description

APPARATUS AND METHOD FOR PRODUCING MOULDED ARTICLES The invention relates to a method and apparatus for producing a moulded article and more particularly to a method and apparatus for producing moulded articles from cellulose pulp and the like.

Pulp, such as cellulose pulp, is often used as packaging in place of polystyrene, as it can be moulded, and is cheaper and more environmentally friendly.

Moulded articles of this kind are usually produced in apparatus which comprises a metal plate, having a series of holes. Shaped gauze moulds are bolted to the underside of the plate, and the upper surface of the plate is connected to a vacuum pump. The bolted assembly is dipped into a container of liquid pulp, and a vacuum is applied to the upper surface of the plate, causing the pulp to be pulled against the gauze into the shape of the gauze mould. The construction is then moved from the container to a conveyor belt, and air is applied in the reverse direction, to push the moulded pulp article away from the gauze mould and onto the belt. The article is then taken through a drying tunnel on the belt, where heat and/or an airstream is applied to it in order to dry it.

A number of problems exist with this process, the two most important ones being firstly that between being released from the mould and being dried, the articles lose their shape, due to their being malleable. This results in deformations which can prevent the article being of use, especially in packaging applications where the shape of the packaging must correspond closely with the shape of the apparatus to be packaged. Secondly, only the side of the article which contacts the mould is acceptably smooth the other side being left rough and unfinished.

It is accordingly an object of the invention to seek to mitigate these disadvantages.

According to a first aspect of the invention there is provided apparatus for moulding an article from a pulp, comprising integral mould means which is fluid-permeable.

According to a second aspect of the invention there is provided apparatus for forming a moulded article from a settable pulp, comprising mould means and setting means, the mould means being adapted to receive pulp and hold same and to facilitate setting of the pulp using the setting means whilst the pulp is in contact with the mould, whereby to form a moulded article.

The mould means may comprise a plurality of moulding elements, and will preferably comprise at least two elements, to contact respective sides of the article being moulded.

The mould means is preferably formed from a porous material which is capable of providing a smooth surface for forming the article, whilst allowing escape of moisture and/or access to drying air.

It is preferred that the mould means comprises a sintered material, and the sintered material may be a metal or ceramic.

The mould means may include vacuum means to facilitate the transfer of material to and from the mould.

The setting means may include a heater to heat the mould means and/or the article. The setting means may further comprise an air blower.

According to a further aspect of the invention there is provided a method of forming a moulded article comprising the step of providing a first mould element, bringing the first mould element into contact with a settable mouldable pulp, applying a second female mould element having a corresponding shape to the first element to sandwich the pulp therebetween, and setting the pulp via the setting means.

It is preferred that pressure is applied to the mould elements when combined.

The pulp may be set in-situ between the mould elements, or alternatively the setting step may be accomplished remotely from the mould.

In order to set the pulp, heat and/or an air stream may be applied to the mould elements.

Apparatus for moulding an article from pulp, and a method of making such an article, are hereinafter described, by way of example, with reference to the accompanying drawings.

Figs. 1 to 3 are a schematic illustrating an apparatus and method for carrying out the invention; and, Fig. 4 is an enlarged cross sectional view through mould elements for use in apparatus embodying the invention.

Referring to the drawings there is illustrated apparatus 1 for forming a moulded article from a settable pulp, comprising mould means 2 and setting means, the mould means 2 being adapted to contact the article over substantially its entire surface area, and to facilitate setting of the pulp via the setting means whilst the article is in contact with the mould.

There is a reservoir or container 4 for a settable pulp 5 in liquid or slurry form, into which the mould face 9 of the mould means 2 is dipped in order to pick up a quantity of pulp for moulding.

In the embodiment shown, the mould means 2 consists of correspondingly shaped interengageable male and female mould parts 6 which are formed from sintered metal or ceramic. The mould parts thus formed are porous. As will be appreciated, the pore size of the material may be varied by varying the size of the metal or ceramic particles used to form the mould parts.

The apparatus 1 is further provided with a vacuum apparatus 7, which is connected by means of a conduit 8 to one of the mould parts 6 in order to provide a suction force to the mould face 9 thereof. This facilitates pick up of pulp onto the mould face 9 for moulding and also serves to draw off liquid in which the pulp is suspended.

In the embodiment, the setting means of the mould is in the form of heating elements 10 disposed within the mould parts 6, and means to apply pressure (not shown) to the mould parts to hold them together when the mould is in use to form an article.

In use, a slurry of pulp 5 is prepared in the reservoir 5. The male mould part is then dipped into the slurry, face 9 first and a vacuum is applied through the conduit to the face 9 to hold the pulp to it, and also to draw off some of the liquid in which the pulp is suspended. The male mould part thus has a coating of pulp. The female mould part which corresponds in shape to the male part is then applied face first to the mould surface of the male part as shown in Figure 2, sandwiching the pulp in between the mould parts 6. Pressure is then applied to the mould parts to hold them together and to compress the layer of pulp 5 sandwiched in between, whereby to effect moulding.

At the same time, heat is applied to the mould part by means of the heating elements 10 and the pulp is dried, and thus set. The mould parts 6 may then be parted in order to remove the article.

As will be appreciated the apparatus of the invention can be used to mould articles from pulp, such as packaging elements, which are moulded over substantially their entire surface areas, thus providing an aesthetically pleasing "finished" appearance, and which are not subject to deformation of shape between moulding and drying, thereby resulting in more precisely formed articles.

Claims

1. Apparatus for moulding an article from pulp, comprising integral mould means which is fluid-permeable.

2. Apparatus for forming a moulded article from a settable pulp, comprising mould means and setting means, the mould means being adapted to receive pulp and hold same and to facilitate setting of the pulp using the setting means whilst the pulp is in contact with the mould, whereby to form a moulded article.

3. Apparatus according to Claim 1 or Claim 2, the mould means being formed from a porous material adapted to provide a smooth surface for forming the article and for drawing moisture from the pulp, and/or for allowing passage of drying air into the mould to effect setting.

4. Apparatus according to Claim 3, the mould means comprising a sintered material.

5. Apparatus according to Claim 4, the mould means comprising a metal or ceramic sintered material.

6. Apparatus according to any preceding claim, the mould means comprising means to apply a vacuum.

Apparatus according to any preceding claim, the mould means comprising a plurality of moulding elements.

8. Apparatus according to Claim 7, comprising two mould elements to contact respective sides of the article being moulded.

9. Apparatus according to any preceding claim, the setting means comprising a heater to heat the mould means and/or the article.

10. Apparatus according to Claim 9, the setting means comprising an air blower.

11. Apparatus for forming a moulded article for pulp, substantially as hereinbefore described with reference to the accompanying drawings.

12. A method of forming a moulded article from pulp, comprising the step of providing a first mould element, bringing the first mould element into contact with a settable mouldable pulp, applying a second mould element having a corresponding shape to the first element to sandwich and shape the pulp therebetween, and setting the pulp via the setting means.

13. A method according to Claim 12, comprising the step of applying pressure to the mould elements when combined.

14. A method according to Claim 12 or Claim 13, including the step of applying heat and/or an air stream to the mould elements to set the pulp.

15. A method of forming a moulded article from a pulp, substantially as hereinbefore described with reference to the accompanying drawings.